Progress 10/01/03 to 09/30/09
Outputs
OUTPUTS: The overall goal of this project was to provide key information and appropriate germplasm to maize geneticists and breeders in order to enable genetic studies to elucidate the inheritance of Western corn rootworm (WCR) resistance and design efficient breeding programs for improving the non-transgenic host plant resistance of maize against WCR. We established an efficient, large-scale field screening method for evaluating maize genotypes for WCR resistance. This phenotyping system is based on the enrichment of experimental fields with WCR larvae using a trap crop. Verification experiments showed that the trap crop is as efficient as manual infestation techniques to determining the degree of resistance of maize genotypes. To account for the spatial variability of WCR larvae in the field, we used advanced statistical designs and models for experiment randomization and analysis as well as for the layout of germplasm screening nurseries. A large set of diverse maize germplasm was screened for WCR resistance using the established evaluation protocol. The resulting data sets were subjected to a quantitative genetic analysis. Due to highly significant genotype-by-environment interactions and large experimental error variances, heritability estimates for WCR resistance traits in maize are low. To account for the low accuracy of separating resistant and susceptible maize germplasm, we modified the evaluation protocol by increasing the number of replications and test locations per experiment. In addition, the level of WCR resistance displayed by inbred lines was not significantly associated with the level of WCR resistance in their hybrid combinations. Therefore, we based our selection on testcross progeny information. In a first phase, base populations developed by the USDA-ARS program "Germplasm Enhancement in Maize (GEM)" were used as germplasm sources. We identified four inbreds with improved WCR resistance from population AR17056:N2025 (AR17059-3, AR17059-4, AR17059-16). In additional cycles of GEM population screening and selection, a set of ten new inbreds with improved WCR resistance and acceptable agronomic performance were developed. Based on their pedigree the improved inbreds carry an average genome contribution of 25% from Brazilian and Argentinean maize germplasm. In a second phase all improved genotypes were recombined to combine different resistance mechanisms. A population of 200 testcrossed double haploid lines (DHLs) was derived from cross AR17059-16 and LH51 to locate genomic regions in maize genome carrying genes involved in WCR resistance. For this population phenotypic data was collected and genetic marker analysis is underway. To ensure long-term selection progress, the Illinois WCR Synthetic was established and Cycle 1 of the recurrent selection program was completed. The idea of employing image analysis procedures and neural networks to assess root damage faster and with higher precision could not be successfully implemented. However, we used the novel devices, software programs, and protocols developed in this project to study the complexity of undamaged root systems and the impact of root complexity on agronomic performance. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The WCR is a serious pest of maize in the U.S. and of growing importance in Europe. Soil insecticides, the use of transgenic maize hybrids producing a Bt toxin, and the rotation of maize with other crops are successfully used to manage WCR populations. However, the occurrence of WCR populations resistant to insecticides and adapted to cultural practices raises the question of how sustainable transgenic control measures against WCR are. In addition, monogenic resistances, like the Bt resistance, might be overcome by the target pest within a short time as amply documented in the literature. It seems, therefore, to make sense to invest in improving the multigenic host plant resistance in corn and to investigate its genetic basis. A major roadblock towards WCR host plant resistant maize genotypes is the apparent lack of genetic variation for these traits in the Midwestern maize pools. This lack of diversity is in stark contrast to the diversity available for improving other quantitative and agronomically important traits, like grain yield, early maturity, or grain composition and emphasizes the need for broadening the genetic basis of the Midwestern maize pools using exotic maize germplasm. We established an efficient screening method as a key prerequisite of a successful breeding program. The developed protocol allowed the screening of a large number of maize genotypes for WCR resistance and, therefore, provided the means to conduct experiments designed to estimate quantitative-genetic parameters associated with WCR resistance. These estimates were critical for optimizing the applied breeding techniques. In order to broaden the genetic base of WCR resistance in maize germplasm adapted to the U.S. Corn Belt, we used source populations provided by the USDA-ARS GEM project, which were derived from crosses between adapted and exotic maize germplasm. In support of our underlying hypotheses that exotic maize germplasm contains unique resistance genes against WCR and that genomic regions carrying resistance genes with an exotic origin can be retained in an adapted maize background if inbred development and selection is conducted under adequate WCR pressure, we selected maize inbred lines with significantly improved WCR resistance. These materials are now used to further investigate the genetic basis and the underlying mechanisms of WCR resistance in maize. In an initial study, inbred AR17059-16 had less root feeding damage, fewer larvae recovered, smaller larvae recovered, and fewer adults recovered than the susceptible controls. These results might indicate that the resistance of AR17056-16 is based on a combination of antibiosis and tolerance.
Publications
- Bohn M. 2008. Development of western corn rootworm resistant GEM germplasm and its role in host plant resistance research. Germplasm Enhancement in Maize Annual Meeting, Chicago, IL, 12/10/2008. www.public.iastate.edu/~usda-gem/.../Yr_08/Bohn_GEM_08_WCR.ppt.
- Bohn, M. 2007. Synergism of traditional and molecular approaches for corn rootworm resistance and susceptibility research - How to breed corn resistant rootworms Annual Meeting of the Entomological Society of America, San Diego, CA, 12/9-12/12/2007. http://esa.confex.com/esa/2007/techprogram/paper_28930.htm.
- Bohn, M. 2005. How to breed corn resistant to corn rootworms Proceedings of the 41th Illinois Corn Breeders School. Urbana, 03/07-03/08/2004.
- Bohn, M. 2004. Long term selection for improving the non-transgenic resistance of corn against the Western corn rootworm. Agronomy Day 2004. http://agronomyday.cropsci.uiuc.edu/2004/Tour_D/selection/index.htm.
- Bohn, M. 2003. Towards maize resistance to stem borers and rootworms. pp. 79-94. Proceedings of the 39th Illinois Corn Breeders School. Urbana, 03/02-03/04/2003.
- Ivezic, M., Raspudic, E., Brmez, M., Majic, I., Brkic I., Tollefson J., Bohn M.O., Hibbard B. and Simic D. 2009. A review on resistance breeding options targeting western corn rootworm (Diabrotica virgifera virgifera LeConte) in Europe. Agricultural and Forest Entomology 11:307-311.
- El Khisen, A.A., Bohn, M.O., Prischmann-Voldseth, D.A., Dashiell, K.E., French, B.W. and Hibbard, B.E. 2009. Native resistance to western corn rootworm (Coleoptera: Chrysomelidae) larval feeding: Characterization and mechanisms. Journal of Economic Entomology. 102: 2350-2359.
- Hibbard, B.E., Flint Garcia, S.A., Bohn, M.O. and Dashiell, K.E. 2008. Native resistance of maize to western corn rootworm larval feeding. In: International Plant Resistance to Insects Workshop Abstracts and Proceedings, February 10-12, 2008, Fort Collins, Colorado. p. 46.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The work in the summer 2008 season was divided into germplasm development and germplasm evaluation related activities. Due to cool temperatures and heavy precipitation at the beginning of the 2008 growing season all GEM experiments and nurseries were planted late at the end of May/beginning of June. WCR experiments and nurseries planted in the WCR trap crop established in 2007 at the SoyFace experiment station in Urbana were flooded during the four to five leaf developmental stages. About 75% of the field, which included the nursery and the WCR evaluation experiments of advanced GEM inbreds, were submerged for more than four days and the retreating surface water further damaged the experiments. Due to the loss of the WCR nursery we were not able to successfully advance our materials under high WCR pressure. In the order to minimize the impact of these adverse conditions, we continued the inbreeding process of materials selected in 2007 in the protected nursery and consequently will increase the size of the WCR nursery in 2009. In addition, 32 F1 hybrids derived from crosses between new GEM lines with increased levels of WCR resistance were selfed to obtain segregating F2 populations. These hybrids were also crossed with an inducer to initiate the production of double haploid lines. Thirty-two newly developed hybrids were evaluated for their agronomic performance in field experiments. In order to develop these hybrids, inbreds obtained from populations DKXL212.N11a01 and AR17056:N2025 were crossed using a factorial design with inbreds obtained from populations BR52060:S0210 and NEI19004:S2818. All 12 inbreds were found to combine improved WCR resistance with acceptable agronomic performance. In general yields were low, ranging from 20 to 127 bushel/acre with a mean of 52 bushel/acre and highly variable. In addition, a set of ten S5 inbreds selected for improved WCR resistance from population DKXL212.N11a01 and crossed to three elite testers was tested for their agronomic performance. Due to the loss of the WCR trap crop location we were not able to evaluate these advanced materials for their level of WCR resistance. Among the testcrosses grain yield varied between 115 and 171 bushel/acre with a mean of 138 bushel/acre. The overall testcross grain yield mean was not significantly different from the overall mean of the commercial check hybrids. The same experiment was conducted in 2007. A combined analysis revealed highly significant (P<0.001) genotype-by-year interactions and large differences between years. The average test cross yield in 2007 was about 60 bushels/acre higher and grain moisture contents at harvest were significantly lower than in 2008. The differences between results obtained in 2007 and 2008 can be partly explained by the late planting date (end of May) and the testcross specific response to this treatment. PARTICIPANTS: Martin Bohn, Associate Professor of Maize Breeding and Quantitative Genetics (University of Illinois, Crop Sciences), is the principle investigator of this project. He is responsible for planning and conducting the breeding nurseries and evaluation experiments. Bohn analyzes the data and makes appropriate selection decisions. He was supported by students working as summer help. The project received in-kind contributions from Pioneer Hibred Inc. and AgReliant Genetics, LLC. These in-kind contributions comprised production of testcrosses. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The Western Corn Rootworm (WCR) is a serious pest of maize in the U.S. and of growing importance in Europe. Soil insecticides, the use of transgenic maize hybrids producing a Bt toxin, and the rotation of maize with other crops are successfully used to manage WCR populations. However, the occurrence of WCR populations resistant to insecticides and adapted to cultural practices raises the question of how sustainable transgenic control measures against WCR are. In addition, monogenic resistances, like the Bt resistance, might be overcome by the target pest within a short time as amply documented in the literature. It seems, therefore, to make sense to invest in improving the multigenic host plant resistance in corn and to investigate its genetic basis. A major roadblock towards WCR host plant resistant maize genotypes is the apparent lack of genetic variation for these traits in the Midwestern maize pools. This lack of diversity is in stark contrast to the diversity available for improving other quantitative and agronomically important traits, like grain yield, early maturity, or grain composition and emphasizes the need for broadening the genetic basis of the Midwestern maize pools using exotic maize germplasm. The underlying hypotheses of this pre-breeding project are: (1) Exotic maize germplasm contains unique resistance genes against WCR, ECB, and Fusarium; and (2) Genomic regions carrying resistance genes with an exotic origin can be retained in an adapted maize background if inbred development and selection is conducted under adequate WCR pressure. The overall goal of this project is the development of maize cultivars, i.e., inbreds and populations, adapted to the U.S. Corn Belt, with improved host plant resistance against WCR by broadening the genetic basis for these characteristics using exotic maize germplasm. The results of this research demonstrate that host plant resistance of maize against the WCR can be improved using exotic maize germplasm. Newly developed inbreds carrying exotic germplasm showed improved levels of WCR resistance under high insect pressure. We are in the process of recombining these improved inbreds with the goal to combine their resistances assuming that each inbred contributes unique resistance genes against WCR. The improved germplasm is also used in quantitative genetic studies to identify the genetic basis of WCR resistance. Together with colleagues from AgReliant and the USDA-ARS (Dr. B. Hibbard, Columbia, Missouri and Dr. K. Dashiell, Brookings, South Dakota), we developed multiple mapping populations. Two of these populations were evaluated for their level of WCR resistance in 2008 and are scheduled to be genotyped with molecular markers in the spring of 2009.
Publications
- Bohn, M.O. 2008. Keynote: How to breed rootworm resistant corn - Synergism of traditional and molecular approaches for corn rootworm resistance research. DIABR-ACT Harmonise the strategies for fighting Diabrotica virgifera virgifera. Goettingen, Germany. May 25-29, 2008.
- Gray, M.E., Sappington, T.W., Miller, N.J., Moeser, J. and Bohn, M.O. 2009. Adaptation and invasiveness of western corn rootworm: Intensifying research on a worsening pest. Annual Review of Entomology 54: 303-321.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The Western corn rootworm (WCR) is a serious pest of maize in the U.S. Whereas the tolerance of maize germplasm adapted to the Midwest against other pests, e.g., the European corn borer, was gradually improved over a 60 year period of continuous selection, improvements regarding WCR resistance are small. One big roadblock towards WCR host plant resistant maize genotypes is the apparent lack of genetic variation for these traits in the Midwestern maize pools. The objectives of this project are to develop maize germplasm with improved WCR resistance and to investigate the genetic basis of this resistance. Activities in 2007 - The different breeding programs initiated in 2003 and 2004 were continued. Based on their per se performance and performance in hybrids, inbreds with improved levels of WCR resistance and good agronomic performance were identified. These inbreds were selected and used to continue the breeding process. In addition, a set of ten new inbreds from the
USDA-Germplasm Enhancement in Maize (GEM) project and 15 new segregating base populations derived from crosses between inbreds improved for WCR resistance were evaluated in the 2007 WCR nursery. Two experiments were conducted to evaluate crosses between new sources of resistance to WCR developed in this breeding program (Experiment 1) and advanced breeding materials for their level of WCR resistance in hybrid combinations (Experiment 2). Experiment 1 -For all agronomic and resistance traits significant differences between hybrids were found. Root damage ratings (Iowa scale, 0 = resistant, 3 = highly susceptible) for the experimental hybrids varied between 0.38 and 2.35 with a mean damage rating of 1.27. Using a base index we identified five hybrids that combine good agronomic performance with high to moderate levels of resistance against WCR. Due to their increased levels of resistance this group of experimental hybrids showed higher base index values than the used commercial non-Bt
check varieties. Experiment 2 - We detected significant differences between experimental hybrids for agronomic and resistance traits. We are now in the process of conducting an in-depth analysis of this experiment with the aim of estimating general and specific combining ability effects. These estimates will provide information about the genetic basis of WCR resistance in the materials tested.
PARTICIPANTS: Martin Bohn, Assistant Professor of Maize Breeding and Quantitative Genetics (University of Illinois, Crop Sciences) is the principle investigator of this project. He is responsible for planning and conducting the breeding nurseries and evaluation experiments. Bohn analyzes the data and makes appropriate selection decisions. He was supported by students working as summer help in 2007. The project received in-kind contributions from Pioneer Hibred Inc., and AgReliant Genetics, LLC. These in-kind contributions comprised production of testcrosses and their agronomic evaluation.
Impacts
The results of this research demonstrate that host plant resistance of maize against the WCR can be improved using exotic maize germplasm. The genetic basis of elite maize germplasm adapted to the U.S. Cornbelt is narrow and specifically for WCR resistance, and no genotypic variance useful for improving this trait is present. Therefore, breeding did not result in maize inbreds with high levels of resistance to WCR. In order to increase the genetic diversity useful for improving WCR resistance, crosses between adapted elite maize inbreds and exotic maize cultivars were evaluated. Newly developed inbreds carrying exotic germplasm showed improved levels of WCR resistance under high insect pressure. We are in the process of recombining these improved inbreds with the goal to combine their resistances assuming that each inbred contributes unique resistance genes against WCR. The first evaluation of these recycled materials in 2007 showed promising results. The F1 hybrids
combined significantly improved levels of WCR resistance with high grain yields. Using these improved materials we are able to conduct genetic studies. The goal of these studies is the identification of quantitative trait loci (QTL) involved in the inheritance of WCR resistance in maize. In order to facilitate these studies, germplasm was developed and AgReliant (a maize breeding company), the USDA-ARS in Columbia, Missouri (Dr. B. Hibbard), and the University of Illinois will conduct a large QTL experiment in 2008.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
The overall objectives of this project are to develop maize germplasm with improved western corn rootworm resistance and to investigate the genetic basis of this resistance. A large set of germplasm was tested in the previous years. The most promising materials were recombined or directly used as base populations for inbred line development. The summer season 2006 was used to evaluate early generations of newly developed materials, advance selected genotypes, and produce testcrosses for early and late generation testing for summer of 2007. In addition, two experiments were conducted to evaluate experimental hybrids derived from crosses between new inbreds with promising levels of WCR resistance for their future usefulness as the basis for new breeding populations and repeat a diallel experiment to investigate the genetic basis of WCR resistance. Germplasm Evaluation (Objective 2): In the winter nursery 2005/2006, a set of eight newly developed inbreds derived from
population DKXL212:N11a01 (obtained from the USDA-Germplasm Enhancement in Maize (GEM) Project) with improved levels of WCR resistance and good general combining ability was crossed with three sources of WCR resistance derived from GEM breeding population AR17056:N2025 identified in earlier germplasm screens. All hybrids were evaluated for WCR resistance in 2006 (Experiment 1). Sixty hybrids representing a half diallel without parents derived from crosses between WCR resistant/tolerant and susceptible inbreds were re-evaluated for WCR resistance and agronomic performance (Experiment 2) to investigate the genetic basis of WCR resistance in maize. For all agronomic and resistance traits significant differences between hybrids in Experiment 1 were found. Hybrid combinations containing AR17056_16 as one parent were characterized by low root lodging. A multivariate analysis was conducted taking all traits into account to identify a hybrid subgroup useful for establishing future base
populations. For Experiment 2 we detected significant differences between experimental hybrids for root damage ratings (RDR) in the combined analysis across years. We are now in the process of estimating general and specific combining abilities for inbreds and their hybrid combinations, respectively. These estimates are of key importance for determining the genetic basis of WCR resistance in maize and the basis of designing efficient breeding programs. Germplasm Development (Objective 3): A set of 210 S5 lines derived from four GEM breeding populations were re-evaluated for WCR resistance using plant performance ratings and root lodging percentages. About 15% of the inbreds were selected and selfed. Based on their per se performance under intensive WCR infestation and agronomic characteristics (earliness, lodging) 479 S3 lines derived from five additional populations were selected in 2005. All S3 lines were re-evaluated for WCR resistance in 2006. Cycle 0 of the Illinois WCR Synthetic
was planted and 150 individual plants (5%) were selected based on phenotypic appearance and selfed. The S1 progenies will be evaluated for their WCR resistance in 2007 and selected genotypes will be recombined in 2008.
Impacts
Four maize inbreds with improved levels of resistance to western corn larvae feeding were identified. These germplasm resources are now extensively used to locate genes involved in the inheritance of western corn rootworm resistance in maize. We conduct these studies in collaboration with USDA-ARS groups in Columbia, Missouri, and Brookings, South Dakota, and AgReliant, a private breeding company. Our research spurred great interest in Europe, where the western corn rootworm was accidentally introduced by seed shipments from the U.S. and where host plant resistance (in contrast to genetically modified cultivars) is the only acceptable WCR control option.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Germplasm Screening (Objectives 1 and 2) - The following GEM germplasm sets were evaluated in Urbana, IL, in 2005: (1) 40 S2 lines derived from GEM populations AR17056:N2025 and CUBA117:S1520 and S3 lines derived from S2 lines selected for their improved WCR resistance in 2004 for testcross and per se performance, (2) a set of 60 hybrids representing a half diallel without parents derived from crosses between inbreds with improved levels of WCR resistance, WCR susceptible inbreds, and inbreds with known contrasting root characteristics, and (3) 162 S2 lines derived from WCR-Breeding Program 2. In all testcross evaluation experiments significant differences between genotypes were detected for root damage rating (RDR) and agronomic characters. The average RDR across all testcross evaluation experiments varied between 0.7 and 2.7 with a total average of 2.0. On average the GEM:NSS-TCs showed less root damage than the GEM:SS-TCs. Testcrosses with GEM lines
DKXL212.N11a01-05-1-2 and DKXL212.N11a01-02-5-2 showed the lowest RDR. Five GEM:NSS-TCs displayed significantly less root damage than the used commercial check hybrids. We detected significant differences between diallel hybrids for RDR and root lodging. The hybrid RDR means varied between 1.10 and 2.68 with an overall mean of 1.84. The mean root lodging values ranged from 4% to 84% with an overall mean of 40%. Significant differences between GCA effects and between SCA effects were found for RDR. For root lodging only significant SCA effects were observed. Inbred CUBA117:S1520-182-1-B-B showed the highest GCA effect for RDR and the smallest GCA effects were observed for B64 and Mo12. Here, negative GCA effects indicate increased levels of WCR resistance. These results confirm observations from the factorial experiment. Based on the observation in our experiments that root lodging and RDR are significantly correlated, we used root lodging information to perform selection in early
generations. A set of 162 newly developed S2 lines were evaluated for root loading resistance under trap crop conditions using an incomplete block design with three replications. Among the 162 lines significant differences for root loading was observed. We selected 30 S2 lines with superior root loading resistance. The total set of 162 was also planted in the nursery for observing agronomic plant characteristics. The inbreeding process was continued for the selected 30 S2 lines. Germplasm Development (Objective 3) - The S3 lines selected in the summer nursery 2004 were selfed in the winter nursery 2004 and two to five ears per S3 line were planted ear to row in the 2005 WCR nursery. Within each row individual plants were selected and selfed. In a second step, whole S3 families were selected based on their testcross performance for WCR resistance. A set of 61 S1 lines derived from four GEM populations and one CIMMYT population were selfed in the winter nursery 2004. Between two to four
selfed ears per S1 line were planted in the summer nursery 2005. Agronomic characteristics for each S2 lines were evaluated. S2 lines with improved WCR resistance were selfed.
Impacts
This project will provide key genetic information and appropriate germplasm to maize geneticists and breeders enabling them to initiate genetic studies to elucidate the inheritance of WCR resistance and to design efficient breeding programs to improve non-transgenic host plant resistance of maize against the WCR. The new breeding program will efficiently combine proven conventional breeding strategies with advanced genomics and bioinformatics methods and approaches. The expectation is that WCR resistant maize cultivars will play an important role in integrated pest management systems.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
To identify new maize germplasm with improved resistance to the Western corn rootworm, 15 base populations from the USDA - Germplasm Enhancement in Maize (GEM) project, 41 inbreds derived from GEM populations AR17056:N2025 and CUBA117:S1520, as well as nine inbreds with known contrasting levels of insect resistance were evaluated for WCR resistance. Three separate field trials (GEM1, GEM1-Pop, and GEM2) were conducted in adjacent fields at the Crop Sciences Research and Education Center, University of Illinois, Urbana, Illinois. The trials were planted in a WCR trap crop area to ensure a high level of infestation. Damage to WCR larval root feeding was measured on five random plants per plot in the line experiments and on ten plants per plot in the population experiment. Root injury was assessed using the Iowa State 0-3 damage rating scale (root damage rating, RDR). The average RDR across all three experiments was 2.6. All evaluated GEM populations and GEM derived S2
families, as well as susceptible and resistant checks showed RDR values larger than 2.14. To broaden the genetic base of non-transgenic WCR resistance in maize adapted to the U.S. Corn Belt by incorporating tropical and subtropical germplasm with improved insect resistance, a total of 500 S2 lines derived from ten GEM base populations were planted ear to row under trap crop enhanced natural WCR infestation. WCR resistance of each S2 line was determined using row appearance and the percentage of root lodged plants per row. Out of 500 rows 25 rows were selected with an acceptable appearance rating and less than ten percent root lodging. Within each row individual plants were selected and selfed. The selected S2 families were derived from five different GEM base populations. A new program was initiated to develop maize germplasm with improved WCR resistance employing a nursery under WCR trap crop. A set of 11 populations was chosen comprising ten GEM base populations and one population
improved for multiple insect resistances at CIMMYT, Mexico. Per population 1,000 plants were grown and a combined selection approach between and within populations was performed. Selected plants were selected and selfed. Between ten and 50 individual plants were selected from a total of five populations. In addition, a diverse set of 81 maize genotypes with high levels of WCR resistance and good root characteristics were random mated to form a base population for a S1 recurrent selection program. The growing season 2004 in East-Central Illinois was characterized by high levels of WCR infestation. The natural high occurrence of WCR larvae together with the trap crop enhanced field infestation resulted in high root damage ratings in our germplasm evaluations. All tested genotypes, including the resistant check and the inbreds that showed host plant resistance in the 2003 evaluation, were severely damaged. This result indicates that the available sources of host plant resistance are not
yet sufficient to withstand extreme high WCR infestations. However, this high level of WCR infestation was productively used to select new GEM derived S2 lines and populations with promising levels of WCR resistance.
Impacts
This project will provide key genetic information and appropriate germplasm to maize geneticists and breeders enabling them to initiate genetic studies to elucidate the inheritance of WCR resistance and to design efficient breeding programs to improve non-transgenic host plant resistance of maize against the WCR. The new breeding program will efficiently combine proven conventional breeding strategies with advanced genomics and bioinformatics methods and approaches. The expectation is that WCR resistant maize cultivars will play an important role in integrated pest management systems.
Publications
- No publications reported this period
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